Knit fabric

ABSTRACT

A multi-layer fabric formed of monofilament threads, each layer having a pattern forming relatively large interstices between the interlocked threads and wherein the two layers are interlocked so that the interstices of one layer are displaced relative to those of the other layer.

United States Patent 1 1 Meyer KNIT FABRIC [76] lnventorz Robert B. Meyer, 25 Luddington Rd., West Orange, NJ. 07052 [22] Filed: June 28, 1971 [21] Appl. No.: 157,240

[52] US. Cl. 66/196 7/1959 France 66/202 Feb. 12, 1974 OTHER PUBLICATIONS Paling, Warp Knitting Technology, 2nd Ed. 1965, Columbine Press, London, pages 119 and 338-342.

Primary Examiner-Ronald Feldbaum 7] ABSTRACT A multi-layer fabric formed of monofilament threads, each layer having a pattern forming relatively large inter'stices between the interlocked threads and wherein the two layers are interlocked so that the interstices of one layer are displaced relative to those of the other layer.

1 Claim, 3 Drawing Figures CYCLE man/ram (F) REM BM (5) provide satisfactory filtering action.

Therefore, one object of the invention resides in the provision of a knitted fabric of a design and pattern that will function among other things as a filter without encountering the aforementioned difficulties.

In accordance with the invention, the above and other objects are achieved by a multi-layer knitted fabric made of hydrophobic monofilament threads, each layer having a relatively loosely woven pattern forming interstices between the knitted threads, and wherein the layers are also interlocked so that the intertwined threads of one layer are disposed opposite the interstices of the intertwined threads of the otherlayer.

These and other objects and features of the invention will become more apparent from the following description and accompanying drawings forming part of this application. I

In the drawings:

FIG. I is a schematic rendering of the fabric of the invention; I

FIGS. 2A, 2B and 2C illustrate lapping formulas used in forming the fabric of FIG. 1; and

FIG. 3 is a photomicrograph of a section of the fabric of FIG. '1.

The fabric of this invention is produced on a warp knitting machine, such as a well known Raschel Warp Knitting Machine of any well-known type having two needle beds and two guide bars. In forming the fabric, monofilament threads, such as polypropylene or other plastic threads of 4 to 12 mils in thickness have been found very satisfactory in that they do not absorb moisture and have sufficient stiffness to preventcollapse of interstices.

As shown in FIG. l, the fabric in accordance with the invention consists of at least two layers of threads la, lb, 1c, etc., and 2a, 2b, 2c, etc., which are knitted in such a way that the threads of the two layers are interwoven or interlocked so that the interstices between the threads of one layer overlie the stitches or interlocking threads of the other layer and vice versa.

As illustrated in FIGS. 2A, 2B and 2C of the drawing, the fabric in accordance with one embodiment of the invention is made on a tWo-needle-bed Raschel Knitting Machine having two half threaded guide bars wherein front guide bar overlaps the rear needle bed while the rear guide bar underlaps on the front needle bed. In forming the fabric, the needles and the guide bars are cyclically moved relative to each other in timed sequence so that the front guide bar knits on the front and back needles, and the back guide bar knits on the back and front needles. In each cycle, as shown in FIG. 2, .the front guide bar is actuated according to the lapping formula 2-0, 4-6, 2-0, 4-6, 8-10, 6-4, 8-10, 6-4, to overlap the front and back needle beds to form stitches while the back guide bar is actuated to underlap the needles of the front and back needle beds. The

back guide bar is operated according to the lapping formula: 8-10, 6-4, 8-10, 6-4, 2-0, 4-6, 2-0, 4-6 to overlap the needles of the front and back needle beds to form stitches while the front guide bar operates to underlap over the needles of the front and back needle beds. Accordingly, the threads of the guide bars are crossed and interlocked to form the fabric.

The repetitive knitting of the threads by the front and back guide bars in accordance with the aforedescribed lapping formulas results in a fabric having a front layer made of threads 1a, 2a, lb, 2b, etc., and a back layer made of threads 2a, la, 2b, lb etc., as shown in FIG. 1, each layer having interstices or openings of substantial size compared to the size of the thread thus providing openings to act as a filter. Were the fabric made of only one layer, solid particles would pass through the openings, thus making the fabric a rather poor filter. However, in accordance with a unique feature of the present invention, a second layer having the same pattern as the first layer is interlocked with the first layer, but this second layer is staggered or shifted relative to the first layer so that the interlocked threads of one layer are disposed opposite the openings or interstices of the other layer. Consequently, solid particles that would pass through one layer are blocked by the interlocked threads of the other layer. It has been found that the utilization of two offset layers do not diminish the filtering quality because the interstices of the overlying layers are staggered and the monofilament threads are relatively stiff. Thus, the resultant porosity is excellent for use in liquid apparatus and particularly apparatus for the purification of blood. In certain applications where fine filters are required,.for example as in the case of filters for air conditioners, the fabric of the present invention may be used by providing a plurality of overlying layers in order to trap all the dust or minute particles.

FIG. 3 is a photomicrograph of a fabric made of monofilament threads of polypropylene woven in accordance with the aforedescribed lapping formulas. It shows rather clearly the porosity of the fabric as maintained by the relatively stiff threads.

Another feature of the present fabric is that the monofilament threads made of a hydrophobic material such as polypropylene do not absorb moisture or water. In addition, the threads are relatively stiff so that they tend to cause the knitted or bent portions to straighten out. This prevents the collapse of the interstices and thus assures retention of good filtering characteristics.

Another advantage of the use of the monofilament threads is that the fabric can be reused by washing or merely shaking the fabric to remove the dust and other particles.

A fabric in accordance with the aforedescribed lapping formula may use partially or fully threaded front and back guide bars depending upon the degree of tightness or sizes of the interstices desired.

While only one embodiment of the present invention is shown and described, other embodiments may be made by modifying the lapping formulas to produce similar structures without departing from the teachings of the present invention.

What is claimed is:

l. A knitted fabric for use as a filter comprising first v and second knitted layers formed of front and back sets of threads with each set of threads being alternately stitched in the first and second layers and with the 4 2-0, 4-6 to form stitches while overlapping on the front and back needles, the threads of the front set being knitted in accordance with the lapping formula 2-0, 4-6, 2-0, 4-6, 8-10, 6-4, 8-10, 6-4 so as to form stitches overlapping on the front and back needles, and said threads being made of hydrophobic monofilaments. 

1. A knitted fabric for use as a filter comprising first and second knitted layers formed of front and back sets of threads with each set of threads being alternately stitched in the first and second layers and with the stitches of one set of threads in each of said layers being disposed between the stitches of the other set of threads, whereby each layer is interlocked and has a pattErn of relatively large interstices between the interlocked threads with the interstices of one layer being displaced relative to those of the other layer, said threads of the back set being knitted in accordance with the lapping formula 8-10, 64, 8-10, 6-4, 2-0, 4-6, 2-0, 4-6 to form stitches while overlapping on the front and back needles, the threads of the front set being knitted in accordance with the lapping formula 20, 4-6, 2-0, 4-6, 8-10, 6-4, 8-10, 6-4 so as to form stitches overlapping on the front and back needles, and said threads being made of hydrophobic monofilaments. 